Probing the symmetry of the potential of localized surface plasmon resonances with phase-shaped electron beams

TL;DR

This paper introduces a novel method using phase-shaped electron beams in a transmission electron microscope to selectively probe and analyze the symmetry properties of localized surface plasmon resonances in metallic nanoparticles, enhancing understanding of their fundamental behaviors.

Contribution

The study demonstrates a new technique for directly accessing and controlling plasmonic excitation symmetries using wave function shaping of electron beams, surpassing previous limitations in plasmon analysis.

Findings

Selective detection of specific plasmon modes achieved

Method allows local probing of individual nanoparticles

Enhanced understanding of plasmonic symmetry properties

Abstract

Plasmonics, the science and technology of the interaction of light with metallic objects, is fundamentally changing the way we can detect, generate and manipulate light. Although the field is progressing swiftly, thanks to the availability of nanoscale manufacturing and analysis methods, fundamental properties such as the plasmonic excitations' symmetries cannot be accessed directly, leading to a partial, sometimes incorrect, understanding of their properties. Here we overcome this limitation by deliberately shaping the wave function of an electron beam to match a plasmonic excitations' symmetry in a modified transmission electron microscope. We show experimentally and theoretically that this offers selective detection of specific plasmon modes within metallic nanoparticles, while excluding modes with other symmetries. This method resembles the widespread use of polarized light for the selective excitation of plasmon modes with the advantage of locally probing the response of individual plasmonic objects and a far wider range of symmetry selection criteria.